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8295
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- 2. • 8295 isa dot matix printer controller • It provides an interface for microprocessors such as www.company.com 8085 and 8086 with dot matrix printers lr7040 • The 8295 is packaged in a 40 pin dip • It can operate both in parallel mode and serial mode with 8085 and 8086 • 8295 includes a 40 character buffer . when the buffer is full or a character return is received a line is printed automatically • The mode selection is parallel by default
- 3. www.company.com PARALLEL INTERFACE • Two register can be accessed by the processor in the parallel mode • The registers are selected as follows
- 4. Two types ofdata can be written in the input data register by the processor : 1.The command to be executed 2.The character data to be stored in the character buffer for printing www.company.com
- 5. • 8295 statusis available in the output status www.company.com register at all times. • If IBF=1 no data should be written to 8295 • DE = 1 , it is in DMA mode • IRQ/SER pin is used an as interrupt in parallel mode
- 6. www.company.com • 8257IS THE DMA CONTROLLER • CONTROL SIGNALS BETWEEN DMA AND PROCESSOR – HOLD ,HLDA ,RD AND WR • CONTROL SIGNALS BETWEEN 8295 AND PROCESSOR – CS , RD ,WR ,RESET AND IRQ/SER • CS , RD, WR PINS ARE USED TO SELECT INPUT OR OUTPUT REGISTER • 8295 CONTROL SIGNALS FOR THE PRINTER INCLUDE MOT , PFM , STB , PFEED AND HOME •
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- 8. www.company.com SERIAL MODE • IRG/SER pin is connected to the ground pin then serial mode is enabled • The serial baud rate is programmed by D2 , D1 , D0 data lines • RD must be high • CS and WR must be low • The processor needs USART like 8251 for serial mode